Device and Apparatus for Efficient Collection and Re-Direction of Emitted Radiation

ABSTRACT

An apparatus is described that includes a light source, a first reflector, a lens and a second reflector. The first reflector is positioned to reflect a first portion of light from the light source, wherein the first portion of light is radiated from the light source in a central forward solid angle as defined by an outer edge of the first reflector. The lens is disposed azimuthally horizontal to the light source for accepting a second portion of light from the light source emitted in a peripheral forward solid angle. The second reflector reflects the first portion of light after reflectance from the first reflector and the second portion of light after passing through the lens in a composite beam, wherein the first reflector and the lens are configured such that the first and second portions of light behave as though they were emitted from a point source at the focus of the second reflector.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of and claims priority underU.S.C. §120 to U.S. patent application Ser. No. 12/873,884, entitled“Device and Apparatus for Efficient Collection and Re-Direction ofEmitted Radiation,” filed Sep. 1, 2010, the entirety of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates the field of light sources using light emittingdiodes (LEDs) and in particular to an apparatus and a method ofcollecting the energy radiating from them. The device could be used ingeneral lighting, decorative and architectural lighting, portablelighting, emergency lighting and many other applications. The inventionis particularly useful when direct visibility to the intense lightsource is undesirable, such as is the case for a dentist's patient.

2. Description of the Prior Art

Most high brightness LED optical solutions exhibit a very annoyingbright LED source, such that viewers in close proximity will bediscomforted at best and distracted or even temporarily ‘blinded’ whenthey ‘look back’ at the apparatus. Several optical solutions place theLED behind a forward mounted reflector that reflects outward a portionof the forward solid angle light emitted by the LED and reflects itagain substantially along the centerline into the original direction ofthe LED. The peripheral forward light from the LED, however is largelyignored or is directed out of the optic peripherally, not along thecenterline. By empirical measurements the beam efficiency of this systemand similar solutions can be less than 50%.

Another means seen in the prior art is the reflex reflector such as thattaught in U.S. Pat. No. 7,001,047. This solution, while showing betterefficiency is typically less than 70% beam efficient, depending onsystem aperture.

What is needed is an optic solution whereby efficient collection ofalmost all of an LED's radiated energy can be obtained and projectedinto an indirect beam with an illumination distribution that is useful.

SUMMARY OF THE INVENTION

The invention is defined as an apparatus comprising an LED light source,a reflector positioned to reflect light from the LED light source whichis radiated from the LED light source in a forward solid angle asdefined by the reflector, and a lens disposed azimuthally horizontalaccepting the peripheral forward solid angle of light from the source ofthe LED, the two objects reflector and lens focusing light into apredetermined radial pattern which is then intercepted and redirectedalong the centerline of the optic and LED by reflection into a compositebeam, so that the apparatus projects a beam of light comprised of thelight radiated in the central forward solid angle and peripheral forwardsolid angles.

The central forward solid angle and the peripheral forward solid angleare demarcated from each other at approximately 45 degrees from theoptical axis of the light source. The light source comprises an LEDemitter and a package in which the LED emitter is disposed. The packagecomprises a package lens for minimizing refraction of light radiatedfrom the LED emitter by the package. The lens is disposed around thepackage lens. In one embodiment the reflector is suspended in front ofthe package lens by means of a leg or legs or a bezel.

The lens directs light radiated by the LED source into the peripheralforward solid angle and likewise the reflector directs light radiated bythe LED source into the peripheral forward solid angle. The secondaryreflector then redirects the two beams into one composite beam. In oneembodiment of the invention the two separately formed beams will appearas if they were one. The designer has control over the individual beams,however, and may tailor the beam output individually or together togenerate the desired result. In another preferred embodiment the beam orbeams would be variable and the adjustment of one or both would providea desired beam effect such as zoom or magnification.

In another preferred embodiment the lens and reflector have a commonpoint of focus that is not the center of illumination of the LED. Thisvirtual focus point is then the focus point of a parabolic reflectorsection that is the secondary reflector. Many variations of this conceptcould include the secondary reflector focus being one of the foci of anelliptical reflector surface.

In the illustrated embodiment the lens is arranged and configuredrelative to the LED light source so that the peripheral forward solidangle extends to a solid angle of approximately 45 to 90 degreescentered on the optical axis. The reflector is arranged and configuredrelative to the LED light source so that the forward solid angle extendsto a solid angle of approximately 0 to 45 degrees centered on theoptical axis.

The invention is also defined as a method comprising the steps ofradiating light from an LED light source, reflecting light into a firstpredetermined beam portion, which light is radiated from the LED lightsource in a forward solid angle, and focusing light into a secondpredetermined beam portion, which light is radiated from the LED lightsource in a peripheral forward solid angle. The central forward solidangle and the peripheral forward solid angle are demarcated from eachother at approximately 45 degrees solid angle centered on the opticalaxis.

In a preferred embodiment of the invention since all the light from theLED is distributed into the two beams and the two beams form a compositebeam treated by the secondary reflector, the secondary reflector canfocus the composite beam into a beam that comprises all of the LED lightthat is not lost in the system to reflection and/or refraction lossesand the system can deliver a very high (approximately 80%) beamefficiency of indirect light.

While the apparatus and method has or will be described for the sake ofgrammatical fluidity with functional explanations, it is to be expresslyunderstood that the claims, unless expressly formulated under 35 USC112, are not to be construed as necessarily limited in any way by theconstruction of “means” or “steps” limitations, but are to be accordedthe full scope of the meaning and equivalents of the definition providedby the claims under the judicial doctrine of equivalents, and in thecase where the claims are expressly formulated under 5 USC 112 are to beaccorded full statutory equivalents under 35 USC 112. The invention canbe better visualized by turning now to the following drawings whereinlike elements are referenced by like numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of an embodiment described herein.

FIGS. 2 a-2 c are side cross-sectional views of the embodiment of FIG.1.

FIG. 3 is an isometric view of the embodiment shown in FIGS. 1 and 2.

FIGS. 4 a-4 c illustrate how the refractor/first reflector combinationof an embodiment operates on emitted light such that the beams thatimpinge upon the second reflector appear to be emitted from a pointsource at the focus of the second reflector, a virtual source.

FIG. 5 illustrates an alternative embodiment described below, having anadditional refractor located in the path of the optical axis of thesource.

FIG. 6 is an alternative embodiment of the invention utilizingcomponents that achieve desired results based on the concept of totalinternal reflection.

The invention and its various embodiments can now be better understoodby turning to the following detailed description of a preferredembodiment which is presented as illustrated examples of the inventiondefined in the claims. It is expressly understood that the invention asdefined by the claims may be broader than the illustrated embodimentsdescribed below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 through 3 illustrate an exemplary device 10 in accordancewith the invention. LED source 1 is shown as packaged in a conventionalpackage, which is generally comprised of a substrate in which the lightemitting junction is encapsulated in a transparent epoxy or plastichousing formed to provide a hemispherical front dome or lens over thelight emitting junction or chip. Many different types and shapes ofpackages could be employed by an LED manufacturer and all types andshapes are included within the scope of the invention. Hereinafter inthe specification the term, “LED source 1.”

FIG. 1 shows a preferred embodiment of the invention in which a firstreflector 3 is suspended over an LED source 1. The surface of the firstreflector 3 may be specially treated or prepared to provide a highlyspecular or reflective surface for the particular wavelengths of lightemitted by LED source 1. In the embodiment presented, the shape of thefirst reflector 3 is concave. This process of surface treatment tomaximize reflectance of select wavelengths is known to those skilled inthe art and will not be detailed herein. In the illustrated embodiment arefractor or lens 2 (hereafter “lens 2”) is shown in FIGS. 1 through 3as having a toroidal, donut-like shape as shown, but is not limited assuch. The shape of lens 2 is determined such that it operates on theazimuthal forward angle light from the LED and processes this light tocreate a narrow beam with pinpoint-like cross-section as viewed andprocessed by a second reflector 4. The first reflector 3 may include orbe connected to an exterior housing (not shown), which provides supportand connection to the apparatus (not shown) in which the device may bemounted. The first reflector 3 could also be suspended or attached or bea part of a planar or non-planar cover lens that projects over theentire optical system. LED source 1 is disposed in the center of secondreflector 4 by any means such as a heat sink or a printed circuit board(“PCB”) (not shown). The first reflector 3 could be suspended over theLED source 1 by means of spider not shown or as part of a bezel or inany other manner (not shown) so as to interfere as little as possiblewith the light exiting the optical system.

As shown in FIGS. 2 a - 2 c showing cross-section A-A from FIG. 1, theLED source 1 is positioned substantially at the center of the circleformed by the outer circumference of the first reflector 3, the LEDsource 1 emitting in the direction of the reflective surface of thefirst reflector 3. The first reflector 3 collects essentially all thelight emitted from the LED source 1 that is radiating into a regionbetween about the forward 45 degree solid angle 6 (referred to as thecenter solid angle) on the centerline or optical axis of the LED source1 and illustrated in FIG. 2 c by the lines referenced at 11 (Ray I).

The rays of light emitted from the LED source 1 that are containedwithin the angles of about 45 degrees and 90 degrees (peripheral forwardsolid angle) 7 as illustrated will be collected by the lens 2 andcontrolled by the optical properties of lens 2 as illustrated in FIG. 2c by the lines referenced at 12 (Ray II). It should be clear to thoseskilled in the art that within FIGS. 2 a-2 c, only half of the ray pathsand configurations are illustrated; a mirror image could be illustratedon the adjacent half of the figures, but has been intentionally removedin order to simplify the illustration. Indeed it should also be clearthat the illustrated rays are duplicated in a complete 360 degree pathin accordance with the light emitted from the LED source. Additionally,it should be apparent to those skilled in the art that there willnecessarily be some overlap at the point where the optical edges of thefirst reflector 3 and the lens 2 meet. It is also contemplated that theembodiments are not limited to an approximate 50/50 split of the light,e.g., 0 to 45 degrees and 45 to 90 degrees. Instead, the emitted lightmay be bifurcated into non-equal parts, so long as the light isprocessed by first reflector 3 and lens 2 to create a narrow beam withpinpoint-like cross-section as viewed and processed by a secondreflector 4. The second reflector 4 combines beams 11 and 12 intocomposite beam 13.

Further to FIGS. 2 a-2 c, reference numeral 5 illustrates annular locusof virtual foci that both the first reflector 3 and the lens 2 create bytheir shape. In a preferred embodiment, the location referenced at 5 isthe actual focus of the second reflector 4. Therefore all the raysemanating from the first two optical elements 2, 3 can be considered bythe second reflector 4 to have a common source. This narrow angle rayset with a single point of focus in cross-section allows the designerfreedom to create a tightly focused, efficient beam utilizingessentially all the light available from the LED source 1, minus surfacelosses (discussed below).

FIGS. 4 a-4 c illustrate an embodiment wherein the first reflector 3 andthe lens 2 are formed so as to create beams that are viewed as thoughthey are generated from a point source at the focus of the secondreflector 4. Referring to FIG. 4 a, the second reflector 4 has aparabolic cross-section (illustrated by curved broken line 20), forinstance, but is not a common parabolic reflector since the surface ofrevolution has a different centerline than the focus (5) of itscross-section. Hypothetical beams B₁ and B₂ are derived from focus 5 andFIG. 4 a indicates how second reflector 4 operates thereon.

Now, referring to FIG. 4 b, it is illustrated how the configuration offirst reflector 3 and lens 2 essentially create beams (11, 12) thatshare a common focus ray set and thus appear to second reflector 4 asthough they are coming from focus or virtual source 5 just ashypothetical beams B₁ and B₂. Accordingly, manipulation of the beams(11, 12) will be very effective and efficient. Said another way, ifbeams (11, 12) were not sharing a common, or near common, focus, anydownstream optical system, such as the secondary reflector 4, would‘see’ a larger source or multiple sources which is known to be lessefficient and less effective than a small singular point source. Thelocation of the virtual source created by the optical configuration canbe varied to some extent and still produce beams that appear as thoughthey derived from a common point source. The virtual focus or source 5can be described as an annular focus as shown in FIG. 4 c.

FIG. 3 is a perspective view of the embodiment of the invention shown inFIGS. 1 and 2. The LED source 1, a radial lens 2, and concave reflector3 are positioned within second reflector 4 as shown in the sidecross-sectional view of FIG. 2.

The invention provides almost complete or 100% collection efficiency ofthe light energy radiated from an LED source 1 for purposes ofillumination, and distribution of the collected energy into a controlledand definable beam pattern. Be reminded that an LED is a light emittingregion mounted on the surface of a chip or substrate. Light from theradiating junction is primarily forward directed out of the surface ofthe chip with a very small amount directed to the sides and slightlybelow the substrate's horizon. Light radiating from the junction intothe substrate is partially reflected, refracted and absorbed as heat.The invention collects substantially all the light, or energy radiatedfrom an LED source 1 which is not absorbed in the substrate on or inwhich it sits and redirects it into two distinct beams of light asdescribed below. By design, these beams could be aimed primarily into asingle direction, but need not be where in an application a differentdistribution of the beams is desired.

The invention collects all of the LED energy in the two regions orbeams(11, 12), wherein a first region 6 is defined by the center solidangle and the second region is defined by the peripheral solid angle 7as described above. The exact angular dividing line between the twobeams can be varied according to the application at hand. Accordingly,while the regions essentially include equal angle covered as exemplifiedherein, this need not necessarily be the case in all embodiments. Theinvention thus controls substantially all of the energy radiating fromthe LED source 1 with only surface and small figure losses. Figurelosses include light loss due to imperfections in some aspect of theoptical system arising from the fact that seams, edges, fillets andother mechanical disruptions in the light paths are not perfectlydefined with mathematical sharpness, but are made from three-dimensionalmaterial objects having microscopic roughness or physical tolerances ofthe order of a wavelength or greater.

In the exemplary embodiment of FIGS. 1, 2 3 and 4 b as shown anddescribed the energy in the first region is reflected via firstreflector 3 that is suspended over the LED 1. The energy in the secondregion is collected via a lens 2. A slight overlap in collection anglescan insure no energy from the LED 1 is leaked between the two regionsdue to the LED emitter being larger than a point source. The resultantbeam can be designed to match system requirements by altering either orboth of the primary elements, the lens 2 or the first reflector 3 or thesecond reflector 4. The invention allows for any of these surfaces to bemodified to control the resultant beam as would be understood by oneskilled in the art.

The first and second reflectors 3 and/or 4 may be designed to provide acollimated, convergent or divergent beam in accordance with designpreferences. The first reflector 3 may be a common conic or not and maybe faceted, dimpled or otherwise modified to provide a desired beampattern. The device 10 may optionally have at least one additional lensand/or surface(s) formed as part of the system that further controls ormodify the light radiating from the first and second reflectors 3 and 4and lens 2.

Thus, it can now be understood that the optical design of lens 2including its longitudinal positioning relative to LED 1 can be changedaccording to the teachings of the invention to obtain the objectives ofthe invention. For example, the nature of the illumination in thecentral solid angle of the two-part beam can be manipulated by theoptical design of lens 2 and first and second reflectors 3 and 4, e.g.the degree of collimation. Further, the dividing line and transitionbetween the two parts of the beam, namely the central and peripheralsolid angles of the beam, can be manipulated by the longitudinalpositioning and radial size or extent of lens 2 relative to LED 1.

In a variation to the optical configuration of FIGS. 1-3 and 4 b, FIG. 5illustrates an embodiment wherein the optical configuration 25facilitates a subset of the emitted light that would have been reflectedfrom first reflector 3, i.e., a portion of the central forward anglelight, being directed through a second refractor 22 instead of the firstreflector 3. In this embodiment, the light emitted from the LED istrifurcated. The lens 2 still operates on the light in the azimuthalangle, but the remaining light is now split between the first reflector3 and the second lens 22.

In an alternative embodiment, the LED light distribution result achievedwith the configuration shown in FIGS. 1 through 3 and 4 b can also beachieved using a device that operates partially (or fully) on theconcept of total internal reflection. More specifically, a molded devicecould include different material interfaces and/or embedded lenses toachieve the light distribution described above. Referring to FIG. 6, LEDsource 1 (including encapsulating lens 8) is attached to a pre-formedoptical device 15 that includes embedded lens 2, which is formed in asecond material 17 that does not affect the light path, but that resultsin total internal reflection of the light passing therethrough at theinterface I₁ of the second material 17 and air. The second material 17and embedded lens 2 forming a first part of the overall molded deviceand being formed so as to receive a second component 19 therein. Thissecond component 19 could be a reflector or a material that causes totalinternal reflection at the interface I₂ thereof with the second material17. As discussed in detail above, a first portion of the light emittedfrom the LED source 1 (represented by ray 11) is reflected by secondpart 19 and is redirected via total internal reflection at theintersection I₁. A second portion of the light emitted from the LEDsource 1 (represented by ray 12) is directed by lens 2 and in thisembodiment, passes through second material 17 and is redirected viatotal internal reflection at the interaction I₁.

Multiple numbers of devices 10 may be arrayed to provide additionalfunctionality. These arrays could include two or more instances of theinvention that may be individually optimized by having a uniqueconfiguration of lens 2 and first and second reflectors 3 and 4. Forexample, an array of devices described above could be used to providemore light than a single cell or unit. The various light sourcesaccording to the invention in such an array could be pointed in selecteddirections, which vary according to design for each element depending onthe lighting application at hand. The elements may each have a differentfocus or beam pattern, or may comprise at least more than one class ofelements having a different focus or beam pattern for each class. Forexample, the invention when used in a wall illumination luminaire may bedesigned in an array to have a broadly spread beam directly under thelamp array, and a closer or more specifically focused spot or ringsending light out to the peripheral edges of the illumination pattern.

Many alterations and modifications may be made by those having ordinaryskill in the art without departing from the spirit and scope of theinvention. The potential range of applications includes, but is notlimited to, dental lights, street lights, parking lights, head torches,bike lights, portable lights (e.g., flashlights), medical head lights,automotive headlights or taillights, motorcycles, aircraft lighting,marine applications both surface and submarine, and any otherapplication where an LED light source might be desired.

Therefore, it must be understood that the illustrated embodiment hasbeen set forth only for the purposes of example and that it should notbe taken as limiting the invention as defined by the following claims.For example, notwithstanding the fact that the elements of a claim areset forth below in a certain combination, it must be expresslyunderstood that the invention includes other combinations of fewer, moreor different elements, which are disclosed in above even when notinitially claimed in such combinations.

The words used in this specification to describe the invention and itsvarious embodiments are to be understood not only in the sense of theircommonly defined meanings, but to include by special definition in thisspecification structure, material or acts beyond the scope of thecommonly defined meanings Thus if an element can be understood in thecontext of this specification as including more than one meaning, thenits use in a claim must be understood as being generic to all possiblemeanings supported by the specification and by the word itself.

The definitions of the words or elements of the following claims are,therefore, defined in this specification to include not only thecombination of elements which are literally set forth, but allequivalent structure, material or acts for performing substantially thesame function in substantially the same way to obtain substantially thesame result. In this sense it is therefore contemplated that anequivalent substitution of two or more elements may be made for any oneof the elements in the claims below or that a single element may besubstituted for two or more elements in a claim. Although elements maybe described above as acting in certain combinations and even initiallyclaimed as such, it is to be expressly understood that one or moreelements from a claimed combination can in some cases be excised fromthe combination and that the claimed combination may be directed to asubcombination or variation of a subcombination.

Insubstantial changes from the claimed subject matter as viewed by aperson with ordinary skill in the art, now known or later devised, areexpressly contemplated as being equivalently within the scope of theclaims. Therefore, obvious substitutions now or later known to one withordinary skill in the art are defined to be within the scope of thedefined elements.

The claims are thus to be understood to include what is specificallyillustrated and described above, what is conceptually equivalent, whatcan be obviously substituted and also what essentially incorporates theessential idea of the invention.

1. A lighting system comprising: a first reflective surface that extendsabout an axis; a second reflective surface that extends about the axis;a ring-shaped aperture formed between the first reflective surface andthe second reflective surface; at least one light emitting diodedisposed along the axis, facing the second reflective surface; and arefractive surface extending about the axis adjacent the at least onelight emitting diode, wherein the first reflective surface and thesecond reflective surface are arranged so that the second reflectivesurface directs first incident light to the first reflective surface,and the first reflective surface directs the first incident light toexit the lighting system through the ring-shaped aperture, and whereinthe refractive surface directs second incident light to the firstreflective surface, and the first reflective surface directs the secondincident light to exit the lighting system through the ring-shapedaperture.
 2. The lighting system of claim 1, wherein the firstreflective surface comprises a surface of revolution with respect to theaxis.
 3. The lighting system of claim 1, wherein the second reflectivesurface comprises a surface of revolution with respect to the axis. 4.The lighting system of claim 1, wherein the refractive surface comprisesa surface of revolution with respect to the axis.
 5. The lighting systemof claim 1, wherein the refractive surface is toroidal.
 6. The lightingsystem of claim 1, wherein the refractive surface comprises a lenshaving a donut-like shape.
 7. The lighting system of claim 1, wherein alens comprises the refractive surface, and wherein the lens comprises anopening through which the axis passes.
 8. The lighting system of claim1, wherein substantially all light emitted by the at least one lightemitting diode that is incident on the first reflective surface has beenincident on at least one of the refractive surface and the secondreflective surface prior to incidence on the first reflective surface.9. The lighting system of claim 1, wherein a portion of light emitted bythe at least one light emitting diode that is incident on the firstreflective surface has been incident on exactly one of the refractivesurface and the second reflective surface prior to incidence on thefirst reflective surface, and wherein another portion of light emittedby the at least one light emitting diode that is incident on the firstreflective surface has been incident on the refractive surface and thesecond reflective surface prior to incidence on the first reflectivesurface.
 10. The lighting system of claim 1, wherein substantially alllight emitted through the ring-shaped aperture has been directed by atleast two of the first reflective surface, the second reflectivesurface, and the refractive surface.
 11. The lighting system of claim 1,wherein in cross section, on one side of the axis, the first reflectivesurface is concave and the second reflective surface is concave.
 12. Thelighting system of claim 1, wherein the second reflective surfacecomprises a point at the axis, the point facing the at least one lightemitting diode.
 13. A lighting system comprising: an optical axis alongwhich light flows; a first reflector through which the optical axispasses; a second reflector disposed circumferentially about the opticalaxis; a ring-shaped aperture, formed between the first reflector and thesecond reflector, through which light exits the lighting system; a lightemitting diode disposed on the optical axis; and a lens extendingperipherally about the light emitting diode and having an openingthrough which the optical axis passes, wherein the first reflectortapers towards the light emitting diode and comprises a reflectivesurface region that is concave in cross section.
 14. The lighting systemof claim 13, wherein the second reflector comprises a profile that issubstantially parabolic.
 15. The lighting system of claim 13, whereinthe lens is torodial.
 16. The lighting system of claim 13, wherein thefirst reflector, the second reflector, and the lens are configured sothat substantially all light emitted from the ring-shaped aperture hasbeen reflected by the second reflector and has been refracted by thelens or reflected by the first reflector.
 17. A lighting systemcomprising: a light emitting diode; a first reflective surface ofrevolution that tapers down towards the light emitting diode and thatprovides an aperture; a second reflective surface of revolution thattapers down towards the light emitting diode and that is disposed in theaperture; and a refractive lens disposed in an opening between the firstreflective surface of revolution and the second reflective surface ofrevolution.
 18. The lighting system of claim 18, wherein the firstreflective surface of revolution is concave, and wherein the secondreflective surface of revolution is concave.
 19. The lighting system ofclaim 18, wherein the second reflective surface of revolution tapers toa point that is pointed at the light emitting diode.
 20. The lightingsystem of claim 18, wherein the refractive lens comprises a donut-shapedlens.